Method and system of single-antenna determination of position, time, and attitude of a moving object by satellite navigation

Abstract

A system for determining position coordinates and attitude coordinates of a moving object employs a plurality of transmitters that transmit navigation signals, the transmitters having known positions and orientations in a given coordinate system. A single antenna that is carried by the moving object receives signals associated with far-field regions of electromagnetic fields of the navigation signals transmitted from the transmitters. A satellite receiver that is carried by the moving object obtains the signals received by the antenna. Phase difference circuitry derives a phase difference between an open circuit voltage of the antenna and a reference phase of a local oscillator in the receiver. A calculation circuit calculates position coordinates and three-dimensional attitude coordinates, within the given coordinate system, of the antenna relative to the transmitters based on the known positions and orientations of the transmitters and the phase difference obtained by the phase difference circuitry. The calculation circuit employs the current time and the position coordinates and three-dimensional attitude coordinates of the antenna in the given coordinate system to derive an attitude of the object relative to a topocentric coordinate system.

What is claimed is:  
     
       1. A method for determining position coordinates and attitude coordinates of a moving object relative to a plurality of transmitters comprising: 
       (a) transmitting navigation signals from a plurality of transmitters having known positions and orientations in a given coordinate system;  
       (b) employing an antenna of a receiver carried by said moving object to receive far-field region electromagnetic fields of said navigation signals transmitted from said plurality of transmitters which contain phase information representing the relative orientation of the receiving antenna with respect to the transmitting antennas;  
       (c) obtaining a phase difference between a reference phase of a local oscillator and the phase information associated with the signal from each transmitter; and  
       (d) calculating, in said given coordinate system, position coordinates and three-dimensional attitude coordinates of said antenna relative to said transmitters based on said known positions and orientations of said transmitters and said phase difference obtained in step (c).  
     
     
       2. The method of  claim 1 , further comprising employing the current time and said position coordinates and three-dimensional attitude coordinates of said antenna in said given coordinate system to derive an attitude of said object relative to a topocentric coordinate system. 
     
     
       3. The method of  claim 1 , wherein said transmitters are mounted on respective satellites. 
     
     
       4. The method of  claim 1 , wherein said transmitters are mounted on the Earth. 
     
     
       5. A system for determining position coordinates and attitude coordinates of a moving object, said system comprising: 
       (a) a plurality of transmitters that transmit navigation signals, said plurality of transmitters having known positions and orientations in a given coordinate system;  
       (b) an antenna that is for being carried by the moving object and that receives signals associated with far-field regions of electromagnetic fields of said navigation signals transmitted from said plurality of transmitters which contain phase information representing the relative orientation of the antenna with respect to the transmitters;  
       (c) a receiver that is for being carried by the moving object and that obtains said signals received by said antenna, said receiver including a local oscillator; and  
       (d) phase difference circuitry that derives a phase difference between an open circuit voltage of said antenna and a reference phase of said local oscillator in said receiver; and  
       (e) a calculation circuit that calculates position coordinates and three-dimensional attitude coordinates, within said given coordinate system, of said antenna relative to said transmitters based on said known positions and orientations of said transmitters and said phase difference obtained by said phase difference circuitry.  
     
     
       6. The system of  claim 5 , wherein said calculation circuit employs the time and said position coordinates and three-dimensional attitude coordinates of said antenna in said given coordinate system to derive an attitude of said object relative to a topocentric coordinate system. 
     
     
       7. The system of  claim 5 , wherein said transmitters are mounted on respective satellites. 
     
     
       8. The system of  claim 5 , wherein said transmitters are mounted on the Earth. 
     
     
       9. The method of  claim 1 , wherein the calculating of the position coordinates and three-dimensional attitude coordinates is done by solving several equations of the form, 
       
         
           ΔΨ s ( t )= k   s ( r   s ( t )− r   s ( t   0 ))−ωΔ t*+δ   s ( t )−δ s ( t   0 )  
         
       
       wherein ΔΨ s (t) is the obtained phase difference of step (c), and δ s (t), r s (t), k s  are functions of the variables we seek: receiver antenna position, x 0   k , k=1, 2, 3, and 3-dimensional receiver antenna attitude specified by the three Euler angles, α, β, γ. 
     
     
       10. The system of  claim 1 , wherein the calculating of the position coordinates and three-dimensional attitude coordinates is done by solving several equations of the form, 
       
         
           ΔΨ s ( t )= k   s ( r   s ( t )− r   s ( t   0 ))−ωΔ t*+δ   s ( t )−δ s ( t   0 )  
         
       
       wherein ΔΨ s (t) is the obtained phase difference of step(d), and δ s (t), r s (t), k s  are functions of the variables we seek: receiver antenna position, x 0   k , k=1, 2, 3, and 3-dimensional receiver antenna attitude specified by the three Euler angles, α, β, γ.